Effect of dietary fibre mixture on growth and intestinal iron absorption in rats recovering from iron-deficiency anaemia

Effects of dietary fiber on intestinal iron absorption, and physiological status: a systematic review of in vivo and clinical studies

The benefits of dietary fiber on intestinal health have been well established. However, there is no consensus on the dietary fiber effects on mineral absorption. The objective of this systematic review is to discuss the evidence on the dietary fiber effects on iron absorption and iron status-related biomarkers. A comprehensive search of 3 databases: PubMed, Scopus and Web of Science was carried out. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, and a total of 32 studies were included with 9 of them clinical studies and 23 in vivo. The studies included assessment of dietary fiber in the form of fructo-oligosaccharides, galacto-oligosaccharides, inulin, pectin, guar gum, oligofructose, xylo-oligosaccharides, and mannan-oligosaccharide. Hemoglobin (n = 21) and fractional iron absorption (n = 6) were the most frequently reported outcomes. The results showed no significant correlations between consumption of dietary fiber to iron absorption/status-related biomarkers. However, the current evidence may not be substantial to invalidate the recommendation of dietary fiber as an agent to improve dietary iron bioavailability, and absorption. In conclusion, there is a need to conduct further clinical trials with long dietary fiber intervention focusing on population at high risk for iron deficiency.

Efecto del consumo del extracto de alfalfa (medicago sativa) en anemia ferropénica inducida, en ratones (mus musculus)

Objetivos Determinar el efecto del consumo del extracto de alfalfa en anemia ferropénica inducida, en ratones.Materiales y Métodos Se utilizaron treinta ratones albinos M. musculus de la cepa Balb/c, machos de peso promedio 23±33,7 g. Se formaron tres grupos de diez ratones cada uno: a) grupo control negativo hierro suficiente (HS), recibió 40g/d de alimento balanceado durante siete semanas; b) grupo control positivo hierro deficiente (HD), recibió 40g/d de dieta ferropénica durante siete semanas y; c) grupo experimental hierro deficiente (HD), recibió 40g/d de dieta ferropénica durante siete semanas y a partir de la semana cinco se agregó 20g/d de extracto de alfalfa (EA).Resultados Al finalizar el tratamiento se observó diferencia significativa en los niveles de hemoglobina entre los grupos control positivo (8.41±3.9 g/dL) y experimental (13.4±3.3 g/dL) (t student, p<0,05). No se encontró diferencia significativa en los niveles de hemoglobina, al término del periodo de inducción entre los grupos control positivo (8.76±3.9 g/dL) y experimental (8.59± 3.1 g/dL) (t student, p>0,05).Conclusiones En condiciones experimentales, la alfalfa presenta efecto antianémico, sustentado en los resultados de los niveles de hemoglobina.

Partially Hydrolyzed Guar Gum Increases Ferroportin Expression in the Colon of Anemic Growing Rats

Studies have reported a positive effect of prebiotics on the bioavailability of iron. This study evaluated the effect of partially hydrolyzed guar gum (PHGG) on iron absorption mechanisms in anemic rats. Male Wistar rats were fed 75g American Institute of Nutrition Rodent Diets for growth, pregnancy and lactation (AIN93-G) without iron for three weeks in order to induce iron deficiency anemia. Then they were fed a control diet (n = 12; without fiber) or a diet with 7.5% of PHGG (n = 12), both without iron. Food intake, body growth and the feed efficiency coefficient (FEC) were measured. The animals were euthanized after two weeks of treatment. The weight of the organs, the pH of the cecal content, and the hepatic iron and ferroportin expression in the cecum, duodenum, and liver were assessed. The intake of PHGG reduced food intake without affecting body growth, and there was a difference between the groups regarding the FEC (p = 0.026), with the highest value found in the PHGG group. The weight of the cecal content increased (p ≤ 0.001) and the pH of the cecal content was significantly lower in the PHGG group. The intake of PHGG significantly increased ferroportin expression in the cecum;however, the difference was not significant in the duodenum and the liver. PHGG seems to have a positive influence on iron absorption through transporter expression, and structural and physiological changes in the colon of anemic growing animals.

Effects of ferrous carbamoyl glycine on iron state and absorption in an iron-deficient rat model

An iron-deficient rat model was established and used to determine the effects of different iron sources on iron metabolism and absorption. Iron-deficient rats were assigned to one of three treatment groups, and their diet was supplemented with deionized water (control), Fe-CGly, or FeSO4 for 8 days via intragastric administration. Blood samples were obtained for analysis of iron-related properties, and the small intestine and liver were removed for quantitative reverse transcription PCR of genes related to iron metabolism. The serum total iron-binding capacity (TIBC) levels of rats in Fe-CGly and FeSO4 supplementation groups was lower (P < 0.05) than that of the rats in the control group. The rats in Fe-CGly group exhibited higher (P < 0.05) plasma Fe and ferritin levels and lower (P < 0.05) TIBC levels compared with the rats in FeSO4 groups. The relative expression of liver hepcidin increased (P < 0.05) by tenfold and 80-fold in the Fe-CGly and FeSO4 groups, respectively, whereas divalent metal transporter 1, duodenal cytochrome b, and ferroportin 1 expression decreased (P < 0.05) in the duodenum in both Fe-CGly and FeSO4 group. A comparison between Fe-CGly and FeSO4 group showed that iron regulatory protein 1 (IRP1) and iron regulatory protein (IRP2) expressions were reduced (P < 0.05) in rats administered FeSO4 than in rats administered with Fe-Cgly. These results indicate that Fe-CGly rapidly improves the blood iron status and that IRP1 and IRP2 may play an important role in the intestinal absorption of Fe-CGly.

Fructo-oligosaccharides and iron bioavailability in anaemic rats: the effects on iron species distribution, ferroportin-1 expression, crypt bifurcation and crypt cell proliferation in the caecum

The present study investigated the effects of fructo-oligosaccharides (FOS) on the bioavailability of Fe from ferric pyrophosphate (FP), a water-insoluble compound, in Fe-deficient anaemic rats that were subjected to a Hb repletion assay. Male Wistar rats (n 64) were fed adequate or low (8 mg/kg) Fe diets for 15 d followed by 1 or 2 weeks of Fe repletion with diets providing 35 mg Fe/kg as ferrous sulphate (FS), FP or FP that was mixed with 7·5% FOS in the form of yacon flour or Raftilose P95 (RAF), a purified source of FOS. The effects of FOS were observed within the 1st week of the repletion period. Fe bioavailability was improved by FOS supplementation, as measured by Hb regeneration efficiency and hepatic Fe stores, which were more pronounced in the RAF group. Moreover, RAF supplementation resulted in a higher biological value relative to that of the FP group. FOS supplementation resulted in caecal enlargement, in addition to acidification and Fe species redistribution in the caecal contents relative to the control rats. These effects occurred concomitantly with decreased ferroportin (FPN)-1 expression in the caecal mucosa, which was similar in magnitude to that observed in the FS group. Caecum mucosal morphometry was influenced by FOS supplementation, whereas crypt fission and cell proliferation were highest in the caecum of the RAF group. These results reinforce the effects of FOS as Fe bioavailability enhancers in anaemic rats that are sustained by early changes in their caecal environment (decreased mucosal FPN-1 expression and increased Fe absorbability, crypt fission and cellularity).

Effect of calcium, tannic acid, phytic acid and pectin over iron uptake in an in vitro Caco-2 cell model

Calcium, phytic acid, polyphenols and fiber are major inhibitors of iron absorption and they could be found in excess in some diets, thereby altering or modifying the iron nutrition status. The purpose of this study is to evaluate the effect of calcium, tannic acid, phytic acid, and pectin over iron uptake, using an in vitro model of epithelial cells (Caco-2 cell line). Caco-2 cells were incubated with iron (10-30 μM) with or without CaCl2 (500 and 1,000 μM) for 24 h. Then, cells were challenged with phytic acid (50-150 μM); pectin (50-150 nM) or tannic acid (100-500 μM) for another 24 h. Finally, (55)Fe (10 μM) uptake was determined. Iron dialyzability was studied using an in vitro digestion method. Iron uptake in cells pre-incubated with 20 and 30 μM Fe was inhibited by CaCl2 (500 μM). Iron uptake decreased in cells cultured with tannic acid (300 μM) and CaCl2 (500-1,000 μM) (two-way ANOVA, p = 0.002). Phytic acid also decreased iron uptake mainly when cells were treated with CaCl2 (1,000 μM) (two-way ANOVA; p < 0.05). Pectin slightly decreased iron uptake (p = NS). Iron dialyzability decreased when iron was mixed with CaCl2 and phytic or tannic acid (T test p < 0.0001, for both) but not when mixed with pectin. Phytic acid combined with calcium is a strong iron uptake inhibitor. Pectin slightly decreased iron uptake with or without calcium. Tannic acid showed an unexpected behavior, inducing an increase on iron uptake, despite its low Fe dialyzability.

High-performance inulin and oligofructose prebiotics increase the intestinal absorption of iron in rats with iron deficiency anaemia during the growth phase

Considering the high frequency of anaemia due to Fe deficiency, it is important to evaluate the effects of prebiotics on the absorption of Fe. The aim of the present study was to evaluate the effects of high-performance (HP) inulin, oligofructose and synergy1 during recovery from anaemia in rats through the intestinal absorption of Fe, food intake, body growth, caecal pH and weight of the intestine. Wistar rats (n 47) were fed with rations of AIN93-G with no Fe to induce Fe deficiency anaemia. At 36 d of life, anaemic rats were divided into four groups: (1) the HP inulin group; (2) the synergy1 group; and (3) the oligofructose group, all with 100 g of the respective prebiotic per kg of ration; and (4) a control group, in which the prebiotic was replaced by maize starch. Then, 25 mg of elemental Fe/kg of ration was added to all rations to allow recovery from anaemia. The final values of Hb in the HP inulin, synergy1, oligofructose and control groups were, respectively: 98 (94–99); 83 (81–92); 100 (90–114); 77 (72–81) g/l, with a statistically significant difference (P ≤ 0·001) between the oligofructose and control groups and the HP inulin and control groups. The four groups had an increase in weight and body length and had similar consumption of rations. The intestinal weight and caecal pH were significantly different between the groups that consumed prebiotics and the control group. HP inulin and oligofructose increased the intestinal absorption of Fe in rats.